CLIMATOLOGY

Figure 1 Concept of climatology;

Ø Is the average condition of the atmosphere near the earth surface over a period of time.

ELEMENT OF CLIMATE AND WEATHER.

Ø Temperature / Solar radiation

Ø Rainfall / Precipitation

Ø Pressure

Ø Wind

Ø Humidity

Ø Clouds

These Elements acted as factors that affect the climate or weather of an area.

THE STRUCTURE AND COMPOSITION OF THE ATMOSPHERE.

Ø The Earth is not quite a sphere, it is technically an oblate spheroid with a radius which varies from 6,356 km at the poles to 6,378.4 at the Equator.

Ø The slight difference is due to the centrifugal effect of the spinning of the planet Earth that causes the Equatorial bulge.

Ø However the Earth is approximately spherical.

Ø The highest mountains are less than 10 km.

Ø Mountains are significance in their influence Temperature.

Ø Atmosphere is a mixture of transparent, odorless gases held to the Earth by gravity as a shallow envelope.

Ø It provides oxygen the vital support system for Human existence.

Ø It allows Temperature condition as thus suitable for life as we know it.

Ø It allows us to communicate by sound.

LAYERS OF ATMOSPHERE.

·      Troposphere

·      Stratosphere

·      Mesosphere

·      Thermosphere

1.   TROPOSPHERE

Ø Begin from 0-16 km from the Earth surface.

Ø Contains water vapour, clouds, dust and pollution.

Ø Pressure fall unstable as a result as the effects of gravity decreases although wind speed usually increase with height.

Ø Temperature decrease with the increase of height.

Ø Support life.

Ø There is a thin layer called “ TROPO PAUSE”  which form upper limit to the earth’s climate and weather. Also marked by an isothermal(equal) layer where temperature remain constant despite any increase in height.

2.  STRATOSPHERE.

Ø Is a second layer beginning from 20-50 kms.

Ø Characterized by a steady of increase in Temperature “ TEMPERATURE INVERSION” caused by a concentration ozone layer { O3}. That absorbs Incoming solar radiation from the Sun.

Ø Winds are light in the lower part.

Ø Pressure continues to fall and Air is dry.

Ø Act as protective shield against meteorites which usually burn out as they enter the earth’s gravitational field.

Ø There is another Isothermal called “STRATO PAUSE”, where the temperature does not change with the increase of heights.

3.   MESOSPHERE.

Ø Is the third layer of the Atmosphere.

Ø Temperature falls rapidly; there is no water vapour, clouds, dust, or ozone to absorb Incoming radiation.

Ø Experience Atmosphere lowest temperature (-90⁰c) and strongest winds nearly 3000 km/hr.

Ø The “ MESO PAUSE” there is no changes in Temperature.

4. THERMOSPHERE.

The temperature rises rapidly with heights perhaps to reach 1500⁰c. athough the Atmosphere behaves in a complex manner and it’s vertical structure is some what complex, measurements of it’s chemical makeup, such as those first made by Regnault in 1852 have shown that the composition of clean Air (Air from which water and unnatural pollutant have been removed, is remarkedbly is constant).

COMPOSITION OF ATMOSPHERE.

GAS                   VOLUME               MASS

N2                        78.09                      75.51

O2                         20.95                     23.15

Argon                    0.93                       1.23

CO2                       0.03                       0.05

Plus trace of hydrogen, hellium, neon, karypton and xenon

PERMANENT GASES.

These are Nitrogen and oxygen make up our 99% volume.

·      Mostly passive in Meteorogical process, oxygen highly active chemical combine with other substance  A rgon not react chemical with other gases varriable gases, occurs naturally:

·      Water vapour

·      Carbon-dioxide

·      Ozone

PERMANENT GASES.

v Water vapour: is important of its response to solar radiation, because change phase, naturally occurring in form of gas (water vapour, liquid water or solid {ice}). It contributes up to a maximum of 4%.

- It’s of course important component of all weather.

v Carbon dioxide: Absorb long wave radiation from the earth; it’s important in the photosynthesis process in plant where by carbon dioxide we exhale is converted into oxygen by plant.

- Oceans contain a large store of dissolved carbon dioxide.

v Ozone: is important constituence non-gaseous.

SOLAR RADIATION.

(ENERGY IN THE ATMOSPHERE)

-The Sun is the prime source energy on the earth.

-Radiates in all directions to space the earth intercept only a fraction (1/2,210- million) of its total output from the distance of some 149,450,000 km.

-The earth receives energy from the sun as an incoming solar radiation {solar radiation}.

Energy is responsible in controlling earth’s climate and weather system.

-Support all forms of life including plant life {photosynthesis}.

FORMS OF ENERGY IN THE ATMOSPHERE.

v KINETIC ENERGY

-Energy which moving atmosphere possesses by virtue of its motion.

v POTENTIAL ENERGY

-Energy which a body of air possesses by virtue of its position owing to the body doing work to overcome the earth gravity.

v LATENT ENERGY

-The heat energy absorbed and held in storage in a liquid or solid during the process of condensation and freezing respectively.

-Energy is required to melt ice (change it’s state) and evaporate water and such energy is released when the water vapour subsequently condenses or the water freezes.

FACTORS INFLUENCING INSOLATION.

The amount of insolation (incoming solar radiation) received by the earth is governed by the following factors

Ø  The solar constant, the flux/ amount of solar radiation, at the outer boundary of the earth’s  atmosphere received on a surface.

Ø Distance from the sun

-When the earth is near to the sun (periphelion) led high amount of insolation received on the earth surface compared to aphelion

Ø Altitude of the sun

-The height above the sea level, when you go far away from the sea level upward the amount of insolation is reduced compared to the same level with sea level.

Ø Latitude

-in tropical and equatorial regions are experienced with high amount of insolation compared to the Polar Regions.

Ø Rotation of the earth

-Lead the occurrence of day (high) and night (low) that cause the variation in amount of insolation.

Ø Cloud cover

-It influence amount of  insolation, it absorb (14%), reflect (35%) and scattering of  insolation.

Ø Albedo

-Amount of solar radiation which is reflected is high in north and south poles compared to tropical region.

Ø Global heat balance

-The balance between incoming solar radiation and outgoing solar radiation.

Ø Green house gases

-like chloro flouro carbon (CFC), carbon dioxide and methane that absorb reflected insolation.

ATMOSPHERIC PRESSURE AND WIND.

-Refers to the circulation of air over the earth’s surface as a result of difference in pressure.

-Atmospheric pressure can be defined as the weight exerted upon the earth by atmosphere. It is the measure of a force exerted by the mass of atmosphere on the surface at a given location especially of temperature and precipitation

WIND

-Is the movement of air in motion from high pressure (low temperature) to low pressure (high temperature).

-The movement of air may be vertical or horizontal

-Wind is the result of differences of temperature and the force that is exerted by gravity as pressure decreases rapidly with height

-Air flow from high pressure to low pressure, because of earth rotation.

v Air flow

Ø In northern deflected Right

Ø In southern deflected left

PRESSURE BELT AND WIND SYSTEM.

There are three major wind system in each hermisphere

vNorthern hermisphere

Ø North east polar winds

Ø South west wind

Ø North east trade winds

vSouthern hermisphere

Ø South east polar winds

Ø North west winds

Ø South east trade winds

vEquatorial